In high-voltage semiconductor drift devices, a well that is supplied with current may be protected by a resistor that is pinched-off during the occurrence of high voltages.
US 2008/0117653 A1 discloses a high-voltage JFET device that works asymmetrically with respect to the source and drain terminals. Because of the low net doping concentration, the lateral resistance is high in the vicinity of the edge of the drift well, and pinch-off voltage and on-resistance cannot both be made as low as desired.
In the paper of T. Karino et al.: “700V PIC Technology Based on 0.35 μm Design for AC-DC Power Units” in Proceedings of the 2012 24th International Symposium on Power Semiconductor Devices and ICs, pages 209 to 212, a HVJFET produced in the 700V-class power IC technology is described.